The Pittsburgh Steelers reached the Super Bowl last season, largely because of the play of an experienced defense. But as quickly as things can change in NFL, a strength can become a point of contention. Fast forward to 2011 and a defense that now features nine players over the age of 30 in the rotation (see box), which begs the question, is the unit too old to compete at a high level?

Regulars on defense in their thirties

Name

Position

Age

James Farrior

LB

36

Aaron Smith

DE

35

Casey Hampton

NT

33

James Harrison

LB

33

Brett Keisel

DE

32

Larry Foote

LB

31

Ike Taylor

DB

31

Ryan Clark

DB

31

Troy Polamalu

DB

30

In taking a closer look at the defense, however, the unit is no worse for the wear. They've ranked among the top five in total defense in six of the past seven seasons, a trend that will continue. Let me give you three reasons why:

1. Dick LeBeau's hallowed zone-blitz system is still effective. The 52-year veteran of the NFL (playing and coaching) has presided over several top defenses during his time as Pittsburgh's defensive coordinator, and his zone-blitz system has been a hallmark of the franchise since the 1990s. The continuity of running the same system over the years has allowed the team to identify, draft and develop players specifically for the scheme.

By relying on a homegrown model, the Steelers are able to develop players and build around their talents as they blossom. With nine starters originally drafted or signed as undrafted free agents, the players have grown up in the scheme and their mastery of the system allows them to play on instincts and awareness.

LeBeau also benefits from having the same core of players. He has a thorough understanding of their strengths and weaknesses as they age, and he's able to tailor parts of his game plan to accentuate their skills even at their advanced ages. With that knowledge, he can keep his players in a position to perform despite their diminishing skills.

2. The chemistry on defense will produce big results. The Steelers' cast of thirtysomethings have been in a ton of battles together. The kinship forged in those contests has developed a level of commitment, accountability and trust that results in outstanding play.

With experience serving as the game's greatest teacher, the defensive core has an invaluable understanding of their identity and how they must perform. That's comes across in their communication and willingness to call out teammates for failing to play up to the standard. It's also revealed in some of the big plays that come from relying on instincts. For instance, Troy Polamalu has picked off balls while freelancing in coverage, but it's Ryan Clark's ability to cover for him in the back end that allows it to happen. Their chemistry gives them the chance to improvise, something that's tough to do without a lot of time together.

3. The Steelers are mixing young talent in with the veterans. Polamalu and James Harrison are the headliners, but it's the emergence of the young defenders that have kept the Steel Curtain intact. Lawrence Timmons (25) and LaMarr Woodley (26) have quietly ascended to the cusp of stardom, which has allowed the team to become less reliant on the veterans. Woodley, in particular, has 35.5 sacks over the past three seasons and is now one of the most dominant rushers in the game.

The team also has two young defensive linemen -- Cameron Heyward (22) and Ziggy Hood (24) -- who are starting to show a readiness for more. The team can slowly integrate them in the rotation to ensure aging stars are fresh for the stretch run of the season. Given the impact of health on a team's title chances, the clever utilization of youth gives the Steelers a chance to make another postseason run in 2011.